The evolutionary status of the bright high-latitude supergiant HD190390

Despite its mean apparent magnitude of m(v)=6.39, the evolutionary status of HD190390 (HR7671), a luminous F-type supergiant at high galactic latitude, is still not very clear, but in most papers a post-AGB classification is assumed. New observational material has been obtained with four different instruments and is presented here. An extensive abundance analysis based on high resolution, high signal-to-noise NTT+EMMI spectra confirms the metal deficiency of this object ([Fe/H]=-1.6), together with a high lithium content (log(Li)=1.9). A variability analysis based on Geneva photometry over seven years reveals beating with a period of +/-3000 days. It is, however, not clear whether this beating is caused by a stable triplet, or it is the consequence of small changes in the main frequency. More recent data obtained with the HIPPARCOS satellite and the Mercator telescope not only confirm the main period, but also support the presence of a second periodicity of 11 days, which was also found in the Geneva photometry. A conclusive evolutionary status of this object is not given, but alternative to the UU Her (i.e. post-AGB) status, a W Vir classification is discussed.Comment: 14 pages, 13 figures, accepted for publication in A&

Esquisse d'hydrosystème céréalier Soudano-Sahélien valorisant les précipitations

L'objectif est de mieux valoriser les précipitations en vue d'améliorer la productivité durablement et de façon rentable pour l'agriculteur. Les écarts constatés entre potentialités et productivités paysannes montrent que cet objectif est possible. L'hydrosystème agricole structure la démarche. Il comprend la partie du système de culture conditionnant les flux hydriques productifs et agissant sur l'environnement. Il est caractérisé par des composants et des indicateurs hydriques de fonctionnement. Les exemples présentés de facteurs de l'hydrosystème céréalier soudano-sahélien, valorisant les précipitations, sont le photopériodisme, l'acidité du sol et le coût des intrants. Des recherches sont suggérées sur d'autres systèmes agricoles tropicaux et d'autres facteurs de l'intensification. Pour les applications de l'hydrosystème au développement, 3 étapes sont schématisées : évaluation-diagnostic de l'alimentation hydrique, simulation de l'hydrosystème agricole optimal et expérimentation-validation. En conclusion, deux orientations pour l'avenir sont proposées pour le développement de la connaissance et de la gestion de l'hydrosystème agricole tropica

Disclosure, Trust and Persuasion in Insurance Markets

This high-stakes experiment investigates the effect on buyers of mandatory disclosures concerning an insurance policy's value for money (the claims ratio) and the seller's commission. These information disclosures have virtually no effect despite most buyers claiming to value such information. Instead, our data reveal that whether the subject is generally trusting plays an important role. Trust is clearly associated with greater willingness to pay for insurance. Unlike in previous work, trust in our setting is not about obligations being fulfilled. The contract is complete, simple and the possibility of breach is negligible. However, as for much B2C insurance marketing, face-to-face selling plays a crucial role in our experimental design. Trusting buyers are more suggestible, so take advice more readily and buy more insurance, although they are no more risk averse than the uninsured. Moreover, trusting buyers feel less pressured by sellers, and are more confident in their decisions which suggests that they are easier to persuade. Therefore, in markets where persuasion is important, public policy designed to increase consumer information is likely to be ineffective.insurance selling, trust, persuasion

HD172481: a super lithium-rich metal-deficient post-AGB binary with a red AGB companion

We present in this paper a study on the peculiar supergiant HD172481. Its spectral type (F2Ia), high galactic latitude (b=-10.37), circumstellar dust, high radial velocity and moderate metal deficiency ([Fe/H]=-0.55) confirm the post-AGB character of this object. A detailed chemical analysis shows slight but real s-process overabundances, however no CNO-enhancement was detected. Furthermore, the spectral energy distribution and the TiO bands in the red part of the spectrum reveal a red luminous companion. The luminosity ratio of the hot F type component and this cool M type companion L(F)/L(M) is derived for a reddening of E(B-V)=0.44 (L(F)/L(M)=1.8) and indicates that the companion must also be strongly evolved and probably evolving along the AGB. Neither our photometric data-set, nor our radial velocity monitoring show evidence for orbital variability which may indicate that the period is too large for direct binary interaction. Most interestingly, a strong lithium resonance line is detected, which yields an abundance of log(Li)=3.6. Several explanations for this large lithium content are explored.Comment: 11 pages, 9 figures, accepted for publication in Astronomy and Astrophysic